• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.126-133
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• 2016

Recently, the research and development of Sodium-cooled Fast Reactors (SFRs) have made progresses. However, liquid sodium, the coolant of an SFR, is chemically unstable and sodium fire can be occurred when liquid sodium leaks from sodium pipe. To reduce the damage by the sodium fire, many fire walls and fire extinguishers are needed for SFRs. LBB concept in SFR might reduce the scale of sodium fire and decrease or eliminate fire walls and fire extinguishers. Therefore, LBB concept can contribute to improve economic efficiency and to strengthen defense-in depth safety. The LBB assessment procedure has been well established, and has been used significantly in light water reactors (LWRs). However, an LBB assessment of an SFR is more complicated because SFRs are operated in elevated temperature regions. In such a region, because creep damage may occur in a material, thereby growing defects, an LBB assessment of an SFR should consider elevated temperature effects. The procedure and method for this purpose are provided in RCC-MRx A16, which is a French code. In this study, LBB assessment was performed for PGSFR IHTS hot-leg pipe according to RCC-MRx A16 and the applicability of the code was discussed.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.63-69
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• 2010

The pre-heat free consumables for GMAW, SAW and FCAW processes that matche with the Cu-bearing PFS-700 steel which has yield strength over 700MPa were developed and evaluated to see the suitability in military such as submarine and battle ship. Explosion Bulge Test underwater was developed and applied to see the reliability of welded structure. All welding was conducted without pre-heat before welding, the interpass temperature was below $150^{\circ}C$ for all welding conditions. Tensile strength for the weld metal in GMAW, SAW and FCAW process is 887MPa, 875MPa and 813MPa, respectively, these values are similar to the base metal of PFS-700 steel of 838MPa. EBT results in GMAW, SAW and FCAW show 14.0%, 14.02% and 15.9% reduction of thickness without generation of crack, respectively and stand-off distance was set up properly to have over 14.0% reduction of thickness. Through EBT results, the developed new consumables are applicable to the weapon systems such as submarine and battle ship.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.702-713
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• 2003

The importance of protection for data and information is increasing by the rapid development of information communication and network. And the concern for protecting private information is also growing due to the increasing demand for lots of services by users. Asymmetric cryptosystem is the mainstream in encryption system rather than symmetric cryptosystem by above reasons. But asymmetric cryptosystem is restricted in applying fields by the reason it takes more times to process than symmetric cryptosystem. In this paper, encryption system which executes authentication works of asymmetric cryptosystem by means of symmetric cryptosystem. The proposed cryptosystem uses an algorithms combines that combines block cipherment with stream cipherment and has a high stability in aspect of secret rate by means of transition of key sequence according to the information of plaintext while symmetric/asymmetric cryptosystem conducts encipherment/deciphermeent using a fixed key. Consequently, it is very difficult to crack although unauthenticator acquires the key information. So, the proposed encryption system which has a certification function of asymmetric cryptosystem and a processing time equivalent to symmetric cryptosystems will be highly useful to authorize data or exchange important information.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.239-244
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• 2006

Borehole radar reflection surveys were carried out in the horizontal borehole to detect EDZ while constructing the tunnel for the research facility of the nuclear waste disposal in Korea. The horizontal borehole has been bored at a length of 35 m from shelter to be parallel with the tunnel which would be planed. While the tunnel has been constructing with the explosive excavation, the borehole radar reflection surveys carried out 5 times with the interval of 2 or 4 days for monitoring EDZ. The most typical change of the reflection event resulted from the face of the wall of tunnel which had been produced newly by the excavation of the tunnel daily, EDZ has been detected with constructing images of difference between two measurement stages, and also the change of EDZ through the time has been done, which is due to the generation of crack and weakening of the rock strength of the face of the tunnel's wall near previous portion of the face of a blind end of tunnel according to explosive excavation.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.63-63
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• 2010

The pre-heat free consumables for GMAW, SAW and FCAW processes that matches the Cu-bearing PFS-700 steel which has yield strength over 700MPa were developed and evaluated to see the suitability in military such as submarine and battle ship. Explosion bulge test in underwater was developed and applied to see the reliability of welded structure. All welding was conducted without pre-heat before welding, the interpass temperature was below $150^{\circ}C$ for all welding conditions. Tensile strength for the weld metal in GMAW, SAW and FCAW process is 887MPa, 875MPa and 813MPa, respectively, these values are similar to the base metal of PFS-700 steel of 838MPa. EBT results in GMAW, SAW and FCAW show 14.0%, 14.02% and 15.9% reduction of thickness without generation of crack, respectively and stand-off distance was set up properly to have over 14.0% reduction of thickness. Through EBT results, the developed new consumables are applicable to the weapon systems such as submarine and battle ship.

• Korean journal of communication and information
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• v.74
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• pp.38-71
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• 2015

Based on the Foucault's governmentality, this study has described the self-government strategy that healing discourse is implemented during 2011-2013. Healing discourse's priority is the existence value of individual and full concentration about self is needed more than anything. In this process, people who need to heal and comfort are limit to de-politicized individuals. Healing discourse emphasizes that the current enhancement in order to become reflection and growth of self. Demands of reflection and growth is substitute the critics of the era and society, but also act as a specific code of conduct to individuals. While emphasizes the reflection and personal growth, healing discourse has top priority of the current value. However, in this process, criticism of the era issues and social structural factors are fundamentally excluded. People accepted healing discourse actively, decided empowering self by reflection and remorse. On the other hand, there is a crack and specificity in the dominant reception discourse likewise some subjects criticized that there is no realistic consolation, exposed the antipathy to the older generation, denied the way of problematized objectification. But this is a partial denial about healing as concrete technology, not fundamental resistance about neoliberal orders.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.45-51
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• 2010

We measured the temperature of target surface inducing by various physical phenomenon on magnetron sputtering target and confirmed the possibilities if the temperature distribution could affect plasma and deposited thin film. The target of magnetron sputtering has two types: round type and rectangular type. In a rectangular target, the concentrated discharge area by corner effect by magnetic field and non-uniform erosion of target are generated. And we found the generation of non-uniform temperature distribution on the target surface from this. This area was $10{\sim}20^{\circ}C$ higher than non-sputtering area. And if particles are generated during sputtering process, they were $20^{\circ}C$ higher than the area where is higher than non-sputtering area. These effects result in non-uniformity of thin films, crack of ceramic target, and shortening target life by non-uniform erosion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1259-1264
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• 2014

Hydrogen is in the world limelight for future energy source, and it has been already used in various industry fields including aerospace. The extremely fine molecule of the hydrogen can be easily leaked from tiny size of the crack on the surface of transporting pipes or storage tanks, and it could bring on awfully terrible disaster. In this study, Laser-Induced Breakdown Spectroscopy (LIBS) was employed to develope a reliable detection scheme for a small quantity of hydrogen leakage. Effect of three different metal substrates (i.e. Al, Cu, SUS) on plasma generation and the intensity of the hydrogen atomic signal was investigated, and the surface damage of the substrates due to repetitive laser shots was observed using Scanning electron microscope. It was also evaluated how the surface damage could distort the atomic signal. The intensity of the atomic signal was found to be the strongest, and the signal distortion due to the surface damage was approximately $100W/m^2$ lower when Al was used for the substrate.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.219-224
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• 2020

The purpose of this study is to develop a device to replace the pre-boring method, which is generally constructed, to prevent pile damage caused by tension cracks that reason from tension waves generated during PHC pile construction on soft ground. Tension cracks are caused by tension waves from the hammer striking during the PHC pile hitting on the soft ground, which in turn leads to faulty construction. In order to prevent the occurrence of tension waves generated during driving, apply separate driving force increasing device to prevent the generation of tension waves, and pile damage as well. Also, it is an eco-friendly construction method that reduces smoke and noise by improving construction speed, reducing construction costs, and able to small equipment when developing equipment. This development equipment is a piece of effective equipment that can pioneer the Saemangeum reclamation area, the South-east Asian construction market, where the Deep soft ground is distributed.

• The Journal of Engineering Geology
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• v.6 no.2
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• pp.59-64
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• 1996

Acoustic Emission(AE) signals are emitted by a sudden release of strain energy associated with material damage. A multi-channels of LeCroy system and piezoelectric pressure transducers are employed for AE measurement to investigate the roles of AE in the propagation of macro cracks as well as the characteris-tics of AE wave in occurrence, amplitude and dominant frequency with changes in macro loading modes. Deduced crack opening volume of micro cracks varied widely and implies that AE events could be caused by crystal dislocations on a small scale and grain boundary movements on a large scale. Amplitude of first arrival AE wave emitted during mode I test was approximately 3 times higher than those from mixed mode test, while the number of AE count in mode I test was only 25% of mixed mode. It may imply that the total energy required for generation of a given fracture surface is similar regardless in change of macroloading modes.